Now you can create an ad-hoc network. Replace your_ssid with the name of the network and frequency with the frequency in MHz, depending on which channel you want to use. See the Wikipedia page List of WLAN channels for a table showing frequencies of individual channels.

# iw interface ibss join your_ssidfrequency

WPA supplicant

Note: This method creates ad-hoc network using WPA encryption. WPA2 is currently not supported (August 2013).